This invention relates generally to the field of fluid dynamics with emphasis on aerodynamic drag phenomena. A particular object of the invention is to reduce energy losses suffered by an aircraft in flight due to induced drag. It is known that this particular type of drag is accompanied by a shedding of vortices from the tips of the wings. It is believed that these vortices result from a spanwise flow of air from a relatively high pressure condition on the lower wing surface to a relatively low pressure condition on the upper wing surface. Similar phenomena occur around hydrofoils employed for underwater use. It might be remarked that air behaves much as a perfect fluid when acting against an airfoil at speeds below about 200 mph and at altitudes below about 100,000 ft. Within that regimen the mathematical tools employed for analysis of airfoils are substantially the same as those for hydrofoils General teachings regarding aircraft drag may be found in classical reference books such as “Foundations of Aerodynamics”, Kuethe and Schetzer, © 1950 by John Wiley & Sons, Inc; “Aerodynamics of a Compressible Fluid”, Liepmann and Puckett, © 1947 by John Wiley & Sons, Inc; “Airplane Performance Stability and Control”, 1949 by Perkins and Hage, publisher John Wiley & Sons, Inc; and in “The Dynamics and Thermodynamics of compressible Fluid Flow”, two volumes by Ascher H. Shapiro, The Ronald Press Company, New York, N.Y., 1953. Reference may also be made to a well known earlier work “Hydrodynamics”, Sir Horace Lamb, 1879, Sixth Ed. by Dover Publications, New York, N.Y., 1945.
The prior art shows numerous techniques for dealing with induced drag, but none are fully satisfactory. Following are some typical examples.                Miranda, U.S. Pat. No. 3,834,654, teaches a box-wing aircraft having a fuselage which is centrally positioned and encircled by six adjoining wing sections.        Wenzel, U.S. Pat. No. 4,146,199 shows an aircraft having a lifting body fuselage surrounded by fore mounted aft swept and aft mounted forward swept wings. The patent describes means for inducing translation of tip-generated vortices.        Wajnikonis, U.S. Pat. No. 4,949,919 discloses hydrofoil families which partially suppress induced vorticity by introducing a longitudinal component of the flow directed by the lifting foil tip towards the hydrofoil base.        Gratzer, U.S. Pat. No. 5,348,253 teaches the attachment of a blended winglet to each wing tip.        Eger U.S. Pat. No. 5,503,352 relates to a box-wing aircraft having wing segment tips connected with arrow-shaped pylons.        Nosenchuck et al. U.S. Pat. No. 5,492,289 has a perturbation proximate to the tip end of the wing planform trailing edge.        McCarthy U.S. Pat. No. 5,634,613 generates beneficial wing tip vortices which are said to rotate in a direction opposite to that of induced drag vortices. The patent asserts that the beneficial vortices create upwash fields which neutralize induced drag. The reference discusses numerous other references dated earlier than 1994.        Frediani U.S. Pat. No. 5,899,409 discloses a large passenger plane having a pair of rearwardly swept wings arranged in tandem with a pair of forwardly swept wings.        Vanmoor U.S. Pat. No. 6,095,457 teaches an airfoil which is reversely curved in accordance with a trigonometric function.        Meschino U.S. Pat. No. 6,340,134 B1 shows an aircraft having a drag reduction system which includes a high aspect ratio, supplementary wing for providing at least 65% of the total lift. The main wing provides structural integrity.        Carlow U.S. Pat. No. 6,474,604 B1 teaches a mobius-like joining structure which is said to reduce vortex-induced drag on a foil.        Huenecke U.S. Pat. No. 6,513,761 B2 discloses the use of vortex generators at the trailing edge of each wing for partly dissipating the vortices responsible for induced drag,        Cox et al. U.S. Pat. No. 6,626,398 B1 teaches an unmanned reconnaissance biplane having staggered and gapped wings.        
While much has been accomplished by others in reducing drag losses of lifting foils, much still remains to be done. It is an undeniable fact that commercial and governmental air transportation expenditures are very high and are steadily increasing. These costs ultimately are passed on to an already overburdened public A substantial proportion of that expenditure pays for fuel which is burned in overcoming induced drag. Even small reductions in that drag may have the potential to create enormous savings for the public.